Source : Free On-Line Dictionary of Computing

exponential-time algorithm
     
         An {algorithm} (or {Turing Machine}) that is
        guaranteed to terminate within a number of steps which is a
        {exponential} function of the size of the problem.
     
        For example, if you have to check every number of n digits to
        find a solution, the {complexity} is O(10^n), and if you add
        an extra digit, you must check ten times as many numbers.
     
        Even if such an algorithm is practical for some given value of
        n, it is likely to become impractical for larger values.  This
        is in contrast to a {polynomial-time algorithm} which grows
        more slowly.
     
        See also {computational complexity}, {polynomial-time},
        {NP-complete}.
     
        (1995-04-27)